A New Class of Tricyclic Diterpenes from Eremophila georgei (Myoporaceae)

1997 ◽  
Vol 50 (7) ◽  
pp. 705 ◽  
Author(s):  
Yana M. Syah ◽  
Emilio L. Ghisalberti ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Spectroscopic Data ◽  
Model Compounds ◽  
X Ray ◽  
New Class ◽  
Relative Stereochemistry

The first example of a new class of tricyclic diterpenes together with two new viscidanes have been isolated from a variety ofEremophila georgei. The structures of the viscidane compounds were assigned on the basis of spectroscopic data and comparison with model compounds. The structure and relative stereochemistry of the lactone (2), which represents a new diterpene skeleton, were established by spectroscopic and X-ray crystallographic methods. The derivation of (2) from a viscidane is suggested.

The chemistry of Eremophila spp. XVIII. A new class of diterpenes from Eremophila viscida

1983 ◽  
Vol 36 (5) ◽  
pp. 993 ◽  
Author(s):  
EL Ghisalberti ◽  
CH Hocart ◽  
PR Jefferies ◽  
GM Proudfoot ◽  
BW Skelton ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Crystallographic Analysis ◽  
X Ray ◽  
New Class

Two new diterpenes have been isolated from the resin of E. viscida Endl. Evidence for their structure was obtained from spectroscopic data and from X-ray crystallographic analysis which show them to be members of a new class of diterpenes containing a C 5 extended acorane skeleton.

scholarly journals Synthesis, structure, and first reactions of a new class of thiacyclophanes

2017 ◽  
Vol 95 (3) ◽  
pp. 278-285 ◽  
Author(s):  
Arunachalam Kannan ◽  
Henning Hopf ◽  
Ina Dix ◽  
Peter G. Jones ◽  
Ludger Ernst
Keyword(s):  
Spectroscopic Data ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
X Ray ◽  
Flash Vacuum Pyrolysis ◽  
New Class ◽  
Product Mixture ◽  
Vacuum Pyrolysis ◽  
Molecular Bridge ◽  
Meta Isomer

In our effort to prepare [m.n]cyclophanes carrying functional groups in their molecular bridges, the thiacyclophanes 14, 19, 20, and 21 have been prepared by simple routes from the pseudo-gem dibromide 10a and the corresponding bis-thiol 10b. The triply-bridged bis-thia-cyclophanes 14, and 19-21 were characterized by their spectroscopic data as well as by X-ray structural analyses. The meta-isomer 20 was oxidized to the bis-sulfone 23, which on flash vacuum pyrolysis (FVP) yielded a product mixture presumably containing the hydrocarbon 26 with a cleaved molecular bridge. Subjecting 23 to Ramberg-Bäcklund conditions (CCl4, NaOH, phase transfer catalysis) provided the chloride 24 in poor yield (9%), a [2.2]paracyclophane in which the new molecular bridge is fully conjugated.

Synthesis and structural characterization of an ether-bridged cobalta-bis(dicarbollide): a model for Venus flytrap cluster reagents

1995 ◽  
Vol 73 (7) ◽  
pp. 1044-1049 ◽  
Author(s):  
David E. Harwell ◽  
Juliet Nabakka ◽  
Carolyn B. Knobler ◽  
M. Frederick Hawthorne
Keyword(s):  
Structural Characterization ◽  
Heavy Atom ◽  
Cobalt Complex ◽  
Monoclinic Space Group ◽  
Model Compounds ◽  
Ether Linkage ◽  
X Ray ◽  
New Class ◽  
Venus Flytrap

The synthesis of bis-(1-carboranylmethyl) ether was first published in 1963; however, its subsequent complexation with a transition metal was never reported. We now report the complexation of cobalt and the corresponding X-ray structure for the triphenylmethylphosphonium salt of the cobalta-bis(carboranylmethyl) ether. The cobalt complex crystallized in the monoclinic space group C2/c with a = 21.729(6) Å, b = 9.845(2) Å, c = 35.565(9) Å, β = 105.363(9)°, V = 7336 Å3, and Z = 8. Data were collected using CuKα radiation, to a maximum 2θ = 115°, giving 4123 unique reflections, and the structure was solved by heavy atom methods. The final discrepancy index was R = 0.093, Rw = 0.100 for 1919 independent reflections with I > 3σ(I). This metala-bis(carboranylalkyl) ether is the first in a new class of Venus flytrap compounds (VFC), containing an ether linkage, to be synthesized as model compounds for the development of reagents suitable for use in the radioimmunodetection and radioimmunotherapy of cancer. Keywords: cobalt, radioimmunodetection, radioimmunotherapy, Venus flytrap.

scholarly journals Synthesis of the reported structure of piperazirum using a nitro-Mannich reaction as the key stereochemical determining step

2013 ◽  
Vol 9 ◽  
pp. 1737-1744 ◽  
Author(s):  
James C Anderson ◽  
Andreas S Kalogirou ◽  
Michael J Porter ◽  
Graham J Tizzard
Keyword(s):  
Single Crystal ◽  
Natural Product ◽  
Mannich Reaction ◽  
Spectroscopic Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Set Up

Piperazirum, isolated from Arum palaestinum Boiss, was originally assigned as r-3,c-5-diisobutyl-c-6-isopropylpiperazin-2-one. The reported structure was synthesised diastereoselectively using a key nitro-Mannich reaction to set up the C5/C6 relative stereochemistry. The structure was unambiguously assigned by single crystal X-ray diffraction but the spectroscopic data did not match those reported for the natural product. The structure of the natural product must therefore be revised.

scholarly journals Spirolucidine, a new Lycopodium alkaloid

1984 ◽  
Vol 62 (2) ◽  
pp. 298-302 ◽  
Author(s):  
William A. Ayer ◽  
Leslie F. Ball ◽  
Lois M. Browne ◽  
Motoo Tori ◽  
Louis T. J. Delbaere ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
X Ray ◽  
Hydride Reduction ◽  
Crystallographic Study ◽  
Lycopodium Alkaloid ◽  
Relative Stereochemistry ◽  
New Type

The structure of spirolucidine, a new type of Lycopodium alkaloid related to the lucidines, has been determined. Chemical and spectroscopic data, together with biogenetic considerations, led to the correct constitution of spirolucidine. An X-ray crystallographic study of tetrahydrodeoxyspirolucidine, the lithium aluminum hydride reduction product of spirolucidine, confirmed the constitution and established the relative stereochemistry of the alkaloid.

Recent Development of Small Molecule Glutaminase Inhibitors

2018 ◽  
Vol 18 (6) ◽  
pp. 432-443 ◽  
Author(s):  
Minsoo Song ◽  
Soong-Hyun Kim ◽  
Chun Young Im ◽  
Hee-Jong Hwang
Keyword(s):  
Small Molecule ◽  
Cell Metabolism ◽  
Phase 1 ◽  
Vital Role ◽  
Glutamine Metabolism ◽  
Inhibition Mechanism ◽  
Tumor Cell Growth ◽  
X Ray ◽  
New Class ◽  
Preclinical And Clinical Studies

Glutaminase (GLS), which is responsible for the conversion of glutamine to glutamate, plays a vital role in up-regulating cell metabolism for tumor cell growth and is considered to be a valuable therapeutic target for cancer treatment. Based on this important function of glutaminase in cancer, several GLS inhibitors have been developed in both academia and industry. Most importantly, Calithera Biosciences Inc. is actively developing the glutaminase inhibitor CB-839 for the treatment of various cancers, and it is currently being evaluated in phase 1 and 2 clinical trials. In this review, recent efforts to develop small molecule glutaminase inhibitors that target glutamine metabolism in both preclinical and clinical studies are discussed. In particular, more emphasis is placed on CB-839 because it is the only small molecule GLS inhibitor being studied in a clinical setting. The inhibition mechanism is also discussed based on X-ray structure studies of thiadiazole derivatives present in glutaminase inhibitor BPTES. Finally, recent medicinal chemistry efforts to develop a new class of GLS inhibitors are described in the hopes of providing useful information for the next generation of GLS inhibitors.

Configuration on the C=N double bond of monosubstituted amidines and amidoximes

1989 ◽  
Vol 54 (12) ◽  
pp. 3245-3252 ◽  
Author(s):  
Bernard Tinant ◽  
Janine Dupont-Fenfau ◽  
Jean-Paul Declercq ◽  
Jaroslav Podlaha ◽  
Otto Exner
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Steric Effects ◽  
Model Compounds ◽  
X Ray ◽  
Analogous Model

Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).

scholarly journals Phenylhydrazone and Quinazoline Derivatives from the Cold-Seep-Derived Fungus Penicillium oxalicum

Marine Drugs ◽  
2020 ◽  
Vol 19 (1) ◽  
pp. 9
Author(s):  
Ya-Ping Liu ◽  
Sheng-Tao Fang ◽  
Zhen-Zhen Shi ◽  
Bin-Gui Wang ◽  
Xiao-Nian Li ◽  
...  
Keyword(s):  
Deep Sea ◽  
Spectroscopic Data ◽  
2D Nmr ◽  
Penicillium Oxalicum ◽  
Marine Phytoplankton ◽  
Cold Seep ◽  
Phytoplankton Species ◽  
X Ray ◽  
X Ray Crystallography ◽  
Quinazoline Derivatives

Three new phenylhydrazones, penoxahydrazones A–C (compounds 1–3), and two new quinazolines, penoxazolones A (compound 4) and B (compound 5), with unique linkages were isolated from the fungus Penicillium oxalicum obtained from the deep sea cold seep. Their structures and relative configurations were assigned by analysis of 1D/2D NMR and mass spectroscopic data, and the absolute configurations of 1, 4, and 5 were established on the basis of X-ray crystallography or ECD calculations. Compound 1 represents the first natural phenylhydrazone-bearing steroid, while compounds 2 and 3 are rarely occurring phenylhydrazone tautomers. Compounds 4 and 5 are enantiomers that feature quinazoline and cinnamic acid units. Some isolates exhibited inhibition of several marine phytoplankton species and marine-derived bacteria.

scholarly journals Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 981
Author(s):  
Mason D. Hart ◽  
John J. Meyers ◽  
Zachary A. Wood ◽  
Toshinori Nakakita ◽  
Jason C. Applegate ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Coordination Chemistry ◽  
Single Crystal ◽  
13C Nmr ◽  
Quantitative Assessment ◽  
X Ray ◽  
New Class ◽  
Linear Relationships ◽  
Ligand Charge Transfer ◽  
Donor Characteristics

Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3.

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